Methods and apparatus to enhance oxygen concentrations for ophthalmic devices

ABSTRACT

Methods and apparatus to enhance levels of oxygen in tear fluid under a worn advanced contact lens are described. The contact lens may include an encapsulated hard lens element which is impermeable to fluid flow across its body. The method of enhancement may include creating pores through the hard lens element, creating channels in portions of the contact lens body, including layers of absorptive material, and creating means of moving tear fluid under the contact lens.

BACKGROUND OF THE INVENTION 1. Field of the Invention

Methods and apparatus to enhance the concentration of oxygen at theinterface of an ophthalmic device with the user's eyes are described. Insome embodiments, the methods and apparatus to enhance oxygenconcentration involve forming pores which are non-perturbative toimagining through the ophthalmic device. In some embodiments, storage ofoxygen is involved. In some embodiments, movement of fluids whichcontain oxygen provides a solution. In some embodiments, a field of usefor the methods and apparatus may include any ophthalmic device orproduct utilizing an embedded hard lens device.

2. Discussion of the Related Art

Recently, the number of medical devices and their functionality hasbegun to rapidly develop. A significant advance has been made in thefield of ophthalmics, where electroactive functions are beingincorporated into ophthalmic lenses. Some embodiments of these devicesmay include components such as semiconductor devices that perform avariety of functions. However, such semiconductor components requireenergy and, thus, energization elements may typically also be includedin such biocompatible devices. The shape and relatively small size ofthe biocompatible devices creates novel and challenging environments forthe definition of various functionalities. In many embodiments, it maybe important to provide safe, reliable, compact and cost effective meanscomprising an insert device to contain the electroactive components andenergization elements within the biocompatible devices. In someexamples, a passive, hard and non-permeable lens device may also preventdiffusion of various materials across their body. The net effect may beto decrease an inherent ability of oxygen to be located on the eyesurface under the ophthalmic device. Therefore, a need exists for novelembodiments of ophthalmic devices to enhance transport of oxygen intothe region proximate to the eye surface

SUMMARY OF THE INVENTION

Accordingly, methods and apparatus to enhance levels of oxygen (whichmay also be called oxygen gas or oxygen molecules) present in the regionbetween a back surface of a worn ophthalmic device and the user's eyeare disclosed.

The cornea receives oxygen from the air and the aqueous humor. Aqueoushumor is blood filtrate which is essentially blood minus the red bloodcells. It is transparent and provides nutrients to both the cornea andthe crystalline lens. The ciliary body provides the aqueous humorthrough the ciliary process. The pre-corneal tear film comprises threelayers. The outermost layer is the superficial oily layer, the innermost layer is the mucoid layer and the middle layer which isninety-eight percent of the tear film is the tear fluid or aqueouslayer. The middle layer is responsible for oxygen uptake to maintaincorneal metabolism. Essentially oxygen from the air diffuses into thetears and is transferred to the cornea via osmosis.

A healthy cornea requires both oxygen and nutrients from the mechanismsdescribed above. Today's silicone hydrogel contact lenses provide forsufficient oxygen transmission from the air to the teats to the cornea.However, advanced contact lenses such as electronic lenses comprisesealed inserts which may potentially limit oxygen transport. There arealso examples of non-electroactive lens systems that incorporate hardlens elements that are encapsulated into a hydrogel exterior, and theselens systems may also have issues with oxygen levels at the user's eyesurface due to impermeability of the hard lens elements. Accordingly,the present invention is directed to various means for ensuringsufficient oxygen transmission to the cornea. In one embodiment,diffusion pores within the body of the encapsulated hard lens elementallow for oxygen diffusion through the encapsulated hard lens elementbody. In another embodiment, the lens may be designed to store anincreased level of oxygen in the body of the lens using variousmaterials or through storage or containment vessels. In yet stillanother embodiment, passive and active pumping mechanisms may beutilized to move oxygen rich fluids around different regions of the eye.

In some examples a contact lens is provided comprising a hydrogel skirtmolded into the shape of a contact lens with an arcuate back surfaceplaced proximate to a user's cornea during a use of the contact lens.The contact lens also includes an encapsulated hard lens element,wherein the encapsulated hard lens element is gas impermeable andimpermeable to fluid flow through its body. The hard lens element isencapsulated within the hydrogel skirt. And, the encapsulated hard lenselement comprises one or more components mounted thereupon. The contactlens has a first region of the hydrogel skirt, wherein the first regionof the hydrogel skirt is that portion of the hydrogel skirt that isbetween a surface of the encapsulated hard lens element and a cornea ofa user during the use of the contact lens. The exemplary contact lensalso includes a means within the contact lens of enhancing oxygen levelswithin a fluid in contact with the first region.

In some examples, the means within the contact lens of enhancing oxygenlevels within the fluid in contact with the first region comprises atleast a first pore in the hard lens element, wherein the pore traversesthe body of the hard lens element. In some examples, the pore isback-filled with a silicone containing material. In some examples, thefirst pore is one of a plurality of pores, wherein the plurality ofpores traverse the body of the hard lens element. In some examples, theplurality of pores are back-filled with the silicone containingmaterial.

In some examples, the means within the contact lens of enhancing oxygenlevels within the fluid in contact with the first region comprises alayer of absorptive material, wherein the absorptive material absorbsoxygen gas. In some examples, the absorptive material compriseshemoglobin. In some examples, the absorptive material compriseshemocyanin. In some examples, the absorptive material comprises aporphyrin based material. In some examples, the absorptive materialcomprises a metal organic framework molecular species.

One general aspect includes methods which enhance oxygen levels at auser's cornea when the user wears a contact lens. The methods mayinclude forming a pore through a hard lens element. Next the method mayinclude backfilling the pore with a silicone containing polymer; andproviding the contact lens comprising the encapsulated hard lenselement, wherein during the use of the contact lens, oxygen diffusesthrough the pore with the silicone containing polymer to a region oftear fluid underneath the contact lens.

Another general aspect includes methods which enhance oxygen levels at auser's cornea when the user wears a contact lens. The method includesforming a layer of oxygen absorptive material within a body of thecontact lens. The method also includes placing the contact lens in anambient with high partial pressure of oxygen. Next the method continuesby providing the contact lens, wherein during a use of the contact lens,oxygen diffuses from the absorptive material to a region of tear fluidunderneath the contact lens.

Another general aspect includes methods which enhance oxygen levels at auser's cornea when the user wears a contact lens. The method includesforming a plurality of channels in an arcuate back curved region of ahydrogel skirt of the contact lens. The method also includes forming araised region of hydrogel skirt above a first enlarged channel in thearcuate back curved region of the hydrogel skirt of the contact lens;and providing the contact lens, wherein during the use of the contactlens an eyelid of the user forces the raised region of hydrogel skirt tocompress the first enlarged channel in the arcuate back curved region ofthe hydrogel skirt, wherein the compression causes tear fluid to moveunderneath the contact lens, wherein the contact lens comprises an hardlens element.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other features and advantages of the invention will beapparent from the following, more particular description of preferredembodiments of the invention, as illustrated in the accompanyingdrawings.

FIGS. 1A-1B illustrate exemplary aspects of contact lenses with inserts,electroactive components and energization elements.

FIGS. 1C-1D illustrate exemplary aspects of a contact lens upon a user'seye with cross sectional focus on the region under the insert above theuser's eye.

FIG. 2A illustrates a cross section of exemplary aspects of a twochamber electroactive optic system within an insert and a hydrogelskirt.

FIG. 2B illustrates a cross section illustrating the cutting of anexemplary through via in an exemplary insert device.

FIG. 2C illustrates a cross section illustrating exemplary filling withhydrogel of the through via in an exemplary insert device.

FIG. 2D illustrates exemplary placement of through vias within the bodyof an exemplary advanced contact lens.

FIG. 2E illustrates an exemplary cross section with multilayer insertand hydrogel skirt with fluted through vias.

FIG. 3A illustrates exemplary incorporation of oxygen absorptivematerial within the body of an exemplary advanced contact lens.

FIG. 3B illustrates exemplary electronically triggered oxygencontainment elements within the body of an exemplary advanced contactlens.

FIG. 4A illustrates a cross section of an exemplary electroactivepumping mechanism within the body of an exemplary advanced contact lens.

FIG. 4B illustrates an exemplary top down view of an electroactivepumping mechanism within the body of an exemplary advanced contact lens.

FIG. 5 illustrates an exemplary passive channel system that may interactwith eyelid blinking to move fluids under an exemplary advanced contactlens.

FIG. 6 illustrates an exemplary contact lens including a hardimpermeable device encapsulated into its body.

FIG. 7A illustrates an exemplary laser process to cut pores through ahard impermeable device which may be encapsulated into a lens body.

FIG. 7B illustrates encapsulating a hard impermeable device including apore with hydrogel encapsulant.

FIG. 8 illustrates exemplary incorporation of oxygen absorptive materialwithin the body of an exemplary contact lens.

DETAILED DESCRIPTION OF THE INVENTION

Methods and apparatus to increase oxygen levels present in the regionbetween an ophthalmic contact lens and a user's eye surface aredisclosed in this application. In some examples, the hydrogel skirt usedto surround an electroactive insert and provide various functionsrelating to an electroactive contact lens may itself be a good medium tofoster the transport of oxygen around the region that intersects with acontact lens. Therefore, in regions of a contact lens with an imbeddedinsert that are on the peripheries of the insert body, there may be verygood transport of oxygen from the air or ambient environment to theuser's eye surface. In some examples, the nature of the formulation,thickness and design of the hydrogel skirt may be aid in realizing acontact lens where sufficient levels of oxygen are present across theuser's eye surface. In other examples, other features of the contactlens may be important to realize good oxygen levels in the regionbetween the back surface of the contact lens and the top surface of theuser's eye, where the intervening region may also include tear fluidfrom the user.

Glossary

In the description and claims below, various terms may be used for whichthe following definitions will apply:

“Biocompatible” as used herein refers to a material or device thatperforms with an appropriate host response in a specific application.For example, a biocompatible device does not have toxic or injuriouseffects on biological systems.

“Coating” as used herein refers to a deposit of material in thin forms.In some uses, the term will refer to a thin deposit that substantiallycovers the surface of a substrate it is formed upon. In other morespecialized uses, the term may be used to describe small thin depositsin smaller regions of the surface.

“Energized” as used herein refers to the state of being able to supplyelectrical current or to have electrical energy stored within.

“Energy” as used herein refers to the capacity of a physical system todo work. Many uses of the energization elements may relate to thecapacity of being able to perform electrical actions.

“Energy Source” or “Energization Element” or “Energization Device” asused herein refers to any device or layer which is capable of supplyingenergy or placing a logical or electrical device in an energized state.The energization elements may include battery cells. The batteries canbe formed from alkaline type cell chemistry and may be solid-statebatteries or wet cell batteries.

“Film” as used herein refers to a thin layer of a material that may actas a covering or a coating; in laminate structures the film typicallyapproximates a planar layer with a top surface and a bottom surface anda body; wherein the body is typically much thinner than the extent ofthe layer.

“Mold” as used herein refers to a rigid or semi-rigid object that may beused to form three-dimensional objects from uncured formulations. Somepreferred molds include two mold parts that, when opposed to oneanother, define the structure of a three-dimensional object.

Exemplary Biomedical Device Construction with Encapsulated Inserts

An example of a biomedical device that may incorporate an insertcontaining energization elements and electroactive elements may be anelectroactive focal-adjusting contact lens. Referring to FIG. 1A, anexample of such a contact lens insert may be depicted as contact lensinsert 100. In the contact lens insert 100, there may be anelectroactive element 120 that may accommodate focal characteristicchanges in response to controlling voltages. A circuit 105 to providethose controlling voltage signals as well as to provide other functionsuch as controlling sensing of the environment for external controlsignals may be powered by an energization element such as abiocompatible battery element 110. As depicted in FIG. 1A, theenergization element may be found as multiple major pieces, in this casethree pieces, and may comprise various configurations of elements. Theenergization elements may have various interconnect features to jointogether pieces as may be depicted underlying the region of interconnect114. The energization elements may be connected to a circuit elementthat may have its substrate 111 upon which interconnect features 125 maybe located. The circuit 105, which may be in the form of an integratedcircuit, may be electrically and physically connected to the substrate111 and its interconnect features 125.

Referring to FIG. 1B, a cross sectional relief of a contact lens 150 maycontain contact lens insert 100 and its discussed constituents. Thecontact lens insert 100 may be encapsulated into a skirt of contact lenshydrogel 155 which may encapsulate the insert and provide a comfortableinterface of the contact lens 150 to a user's eye.

Referring to FIG. 1C, the cross sectional relief of FIG. 1B isillustrated superimposed upon a user's eye 170. There may be regions onthe surface of the user's eye that may lie under a region of the lensthat contains an insert such as region 190. And, there may be regions onthe surface of the user's eye that may lie under only the hydrogel skirtsuch as region 180. In some examples the level of oxygenation in aregion of tear fluid and surface tissue may be less in region 190 thanin region 180 due to the inhibition of oxygen diffusion from an ambientgas which may be located exterior to the contact lens to the surface ofthe user's eye. In these examples, other design aspects of the contactlens with encapsulated insert may be warranted.

Referring to FIG. 1D, a cross sectional blow up of a portion of theregion 180 under an insert is illustrated. A surface of the user's eye181, or cornea is illustrated. Above the surface of the user's eye 181may naturally occur a thin layer of tear fluid 182 that the lens issupported upon. On the other side of the thin layer of tear fluid 182may be a portion of the hydrogel skirt 183. The shape of the hydrogelskirt which is proximate to a user's cornea or eye may be called anarcuate surface, and this surface may also be called the back surface orback curve surface therefore it may be an arcuate back surface or anarcuate back curved surface. The cross section of FIG. 1D is illustratedat the edge of the lens insert 184. Therefore, a variable thicknesslayer of the lens skirt 185 above the lens insert 184 is illustrated.The region of the hydrogel skirt under the insert and the associatedportion of the layer of tear fluid under the insert may be a region ofdecreased oxygen levels due to the fact that the lens insert 184prevents diffusion through its body and the user's eye 181 is consumingoxygen. The tear fluid 182 may also have decreased oxygen level.

Diffusion “Pores” within the Body of an Encapsulated Insert.

Referring to FIG. 2A a cross section of an encapsulated insert isillustrated. In the example, a dual chamber insert may be found. Anouter layer may form a top surface 211 of the insert. And, another outerlayer may form the bottom surface 214 of the insert. In some examples,these insert surfaces may have shapes and forms to relate to desiredoptical effects of the insert structure such as being shaped to addpower to the lens effect of the insert. In examples with multiplechambers, such as illustrated in FIG. 2A, an intermediate piece 217 mayalso be formed. In a likewise fashion to the outer layers, theintermediate piece 217 may be shaped to related to optical effects ofthe lens structure. In some examples, the chambers may have internalstructures which may define the structural height of a chamber in aregion. These structures may be called spacer's. The first chamber 212may have a first chamber spacer 213 and the second chamber 215 may havea second chamber spacer 216. In some examples, the location of thespacers may be unrelated to each other, in the example illustrated theymay align which may allow for a pore to be formed in the center of themwhich penetrates through the entire body and out of each insert surface.The spacers may be located in the chambers in regions that are locatedin the optic zone of the ophthalmic lens, where the optic zone is theportion of the lens where light passes through from an object on its wayto the user's retina. If the spacer is located in the optic zone, it mayinteract with the light rays passing through forming an image.Therefore, it may be important that the spacer is kept to a minimalsize. In some examples, the size may be less than 100 microns. Infurther examples, the size may be less than 50 microns. In still furtherexamples the size may be less than 20 microns.

A spacer column may be formed by the overlay of the first chamber spacer213 and the second chamber spacer 216. Referring to FIG. 2B, the cuttingof a pore 221 is illustrated. In some examples, the pore may be cut by alaser light source 220. As an example, a Ytterbium fiber based laser maybe focused to drill holes in materials such as plastics with dimensionsas small as 10-20 microns in size. Any laser drilling type equipment maybe used to create the pore through the top surface 211, the firstchamber spacer 213, the second chamber spacer 216 and the bottom surface214. In some examples other methods of creating a pore may be utilizedsuch as in a non-limiting example a photolithography process to image aphotoresist mask followed by a reactive ion etching process through thelayers. Any technique to drill a small profile hole through insertpieces may be utilized.

The pore 221 may be a path that allows oxygen to diffuse through theinsert from the front of the electroactive lens to the back of theelectroactive lens. If the pore exists in an encapsulated lens, thediffusion of tear fluid through the pore along with dissolved oxygen inthe tear fluid may enhance oxygen levels along tissues of the user's eyesurface under the lens insert region (as was depicted as 180 in FIG.1C). In some examples, oxygen permeation may be very effective inhydrogel layers. Referring to FIG. 2C, a hydrogel layer 230 used toencapsulate a lens insert may also fill (or “back-fill”) the pore with alayer of hydrogel in the pore 231. Oxygen may diffuse through tear fluidand hydrogel from a front surface through the lens body and into thehydrogel layers on the back surface of the lens and ultimately into alayer of tear fluid between the lens and the eye surface where it canthen diffuse to the tissue layers of the eye.

Referring to FIG. 2D, a top down view of a lens insert with poresdrilled through the body in various locations is illustrated. Asillustrated, in an example, there may be five (5) holes cut into theinsert device at features 271,272,273, 274 and 275. The actual number ofpores may be more or less than those illustrated depending on a numberof factors including factors such as degradation in imaging through thelens by the presence of pores and the effectiveness of increased oxygenlevels versus distance from a pore. There may be other factors thatimpact the design of the pores individually and their pattern and numberin the insert body.

It may be desirable to form the pore with a diameter on the order ofapproximately 20 microns. In order to fill the pore with hydrogelmonomer, it may be desirable to evacuate the pore of gasses beforefilling a mold with monomer around the insert. By evacuating the gasphase around and within the pore, a better filling with monomer mayresult.

Referring to FIG. 2E an exemplary contact lens is illustrated in crosssection. The contact lens skirt 280 in cross section, and 281 view frombehind may surround an insert. The insert may have two chambers, a firstchamber 283 and a second chamber 284. Through vias or holes areillustrated such as the exemplary through via 282. As illustrated, thelaser drilling processing may result in profiles to the holes that arefluted with wider diameter near the surface of the lens.

Oxygen Absorption and Desorption

Another manner to increase oxygen in the space between an advancedcontact lens and the eye surface may be to store an increased level ofoxygen in the body of the lens. The increased level may be imparted tothe lens by storing the lens in a pressurized oxygen environment beforepackaging the lens. There may be a number of material additions tolayers in the lens that may impart the ability to store oxygen from thepressurized atmosphere. Ideally the materials that store the oxygen willdesorb the oxygen as the level of oxygen in its vicinity drops. In otherexamples, the stored oxygen may be desorbed under an influence such asby the heating of the material.

Referring to FIG. 3A, a layer of absorptive material 310 may be embeddedwithin an advanced contact lens. The general structure of the insertexample is illustrated as in previous depictions including a top surface211, a first chamber 212, a first chamber spacer 213, a bottom surface214, a second chamber 215 and a second chamber spacer 216. In someexamples, there may be a through via or pore 221. In some examples, theabsorptive material 310 may be deposited on the surface of the insert.In other examples, it may be embedded within the hydrogel skirt layer asa film or as in entrapped discrete elements. In some examples, theabsorptive material 310 may be synthetic organometallic moieties basedupon natural oxygen transport molecules or may be biological oxygentransport molecules such as hemoglobin, hemocyanin, another porphyrinbased species or another metal organic framework molecular species. Theabsorptive material 310 may comprise metallic species such as iron,copper, and zirconium as non-limiting examples. These organometallicspecies may be integrated into the hydrogel layer and may reversiblydesorb oxygen into the hydrogel layer. In some examples, desorption maybe stimulated by electrical action on the layers of absorptive material,such as heating them. Due to the nature of the use environment, suchheating may be limited to small regions of the absorptive material at atime. Other similar organic molecules may be embedded to perform asimilar function.

In other examples, the absorptive material may comprise absorptiveparticles, such as zeolites that may be charged with oxygen. Theparticles may maintain an equilibrium level of oxygen in theirsurroundings. Therefore, when a package containing the advanced contactlens device is opened for use, a release of oxygen may occur, and theabsorptive particle may begin desorbing oxygen. In some examples, theabsorptive material may include zeolites of various composition such assodium, cerium, silicon and aluminum for example. In other examples theabsorptive/adsorptive material may comprise polymers and doped polymerswhich absorb oxygen, such as polymers with unsaturated regions orphenolic regions in the backbone. Polymers may be doped with otherspecies such as copper for example in a polyester and poly-butadienestructure. A super saturation of these absorptive particles under highpressure, high concentration and/or high partial pressure of oxygen, mayresult in a material that releases oxygen in low levels over time whenthe oxygen level in the ambient drops.

Referring to FIG. 3B, an alternative but related device structure isillustrated. The general structure of the insert example is illustratedas in previous depictions including a top surface 211, a first chamber212, a first chamber spacer 213, a bottom surface 214, a second chamber215 and a second chamber spacer 216. In some examples, there may be athrough via or pore 221. A surface of the insert may be formed tocomprise a series of oxygen containment or oxygen generation vesselsshown as vessels 350. In some example the vessels 350 may containpressurized oxygen. An electrically controllable release feature 360 maybe formed upon the vessel containing the pressurized oxygen and upon anelectric signal may release the oxygen. In some examples, the electricalsignal may cause a thin metallic foil to melt in the process ofreleasing the stored oxygen.

In other examples, the vessel 350 may contain a segregated region of anoxygen containing chemical such as hydrogen peroxide. The electricallycontrollable release feature 360 may in these cases release hydrogenperoxide to flow into another region of the device where it may interactwith a catalytic surface, such as the surface of zeolites, where theperoxide may decompose into water and evolved oxygen. In some examples,the vessel may be capped with a membrane that may allow oxygen todiffuse through while containing the other components such as thecatalytic surface within the vessel.

The electroactive oxygen generator or releasing structure may beelectrically programmed to be released at a particular time after a usecycle begins. A large number of these features may therefore be slowlyand regionally triggered to enhance oxygen levels during a use cycleacross regions underneath an insert of an advanced contact lens.

Movement of Oxygen Rich Fluids to Enhance Oxygenation

The general environment around an advanced contact lens during its usehas ample levels of oxygen. However, in some cases the inhibition ofdiffusion through a contact lens by a sealed insert may be coupled withthe fact that the thin layer of tear fluid between the hydrogel surfaceof the contact lens and the eye surface may not move significantly toexchange with more oxygenated regions peripheral to the insert region.In practice the hydrogel layers may provide effective transport ofoxygen from peripheral regions towards regions under the insert, but thetissue in those regions may be consuming oxygen at a significant rate.Thus, if enhanced oxygen transport may be needed, it may be useful toenhance the movement of tear fluid under the insert region into and outof that region.

Referring to FIGS. 4A and 4B an electroactive pump 410 may be used tomove fluid, more specifically tear fluid proximate to a user's eyesurface. The general structure of the insert example is illustrated inFIG. 4A as in previous depictions including a top surface 211, a firstchamber 212, a first chamber spacer 213, a bottom surface 214, a secondchamber 215 and a second chamber spacer 216. In some examples, there maybe a through via or pore 221. As a relevant aside, if the tear fluid andhydrogel materials are matched relative to their index of refraction itmay be possible to create channels 420 in the hydrogel that may fillwith tear fluid, but which may not create an optically interactingstructure. In some examples, when illustrated from top down, channelsmay be formed to include flow directing aspects, such as flap valves orprofiled surfaces which may favor one direction of flow rather thananother. In some examples, the height of such a channel may be less thanapproximately 20 microns and the width may be approximately 20-50microns. In further examples, the height of such a channel may be lessthan approximately 5 microns. In still further examples, the height ofsuch a channel may be less than approximately 1 micron. There may benumerous examples of heights and widths outside these exemplary amounts.

When illustrated from top down, an inward flowing channel 430 and anoutward flowing channel 440 is illustrated. Again, very small featuresmay be molded into the hydrogel to form these channels and the analog offlow check valves into the shape of the channels. The electroactive pump410 may be comprised of a portion that expands or contracts upon anelectrical signal, such as a piezoceramic or piezoelectric basedtransducer or electroactive elastomer or electroactive polymer basedtransducer. By contracting an electroactive body 411, an attachedhydrogel feature 412 may move opening up the volume in a chamber 413under the device. When the volume is opened up, fluid may be drawn intothe chamber 413. In the opposite case, when the electrical signal isremoved or reversed, the electroactive body 411 may expand, move downthe hydrogel feature 412 and cause fluid in the chamber 413 to be pushedout of channels.

Thus, oxygen laden fluid may be moved from peripheral regions through anetwork of channels under the insert region of an advanced contact lens.In some examples, a relatively slow and steady pumping action may resultin the user not being perturbed either physically or optically duringthe pumping action. In some other examples, the pumping action may beprogrammed to be intermittent and may, for example, coincide with adetection of blinking of the eye.

Referring to FIG. 5 a similar channel based distribution of oxygenatedfluid is illustrated where the pumping mechanism may be passive, i.e.may not involve an electroactive pump. When a user's eye lid blinks itmay impart force to engage a pumping mechanism. In some examples, theforce may compress channels and allow for fluid to be squeezed out ofthe channels in the region under the insert 511 to the peripheral region510. After the lid moves by, the channels may again expand drawing newoxygen laden fluid in from the peripheral regions. In another example,there may be protrusions 520 in the peripheral regions of the lens thatare forced downward as the user's eyelid goes by them in bothdirections. With an appropriate level of flow direction (i.e. checkvalve type action) in the channels, the force downward on theprotrusions and their effect on neighboring regions may pump fluid alonga network of channels 530 exchanging fluid from external regions tointernal regions. In some examples, the channels 530 may be formed intoa hydrogel encapsulating skirt and may be approximately 50 microns orless in height and a width that maintains the presence of a channel whenthe contact lens is worn. As an example, the width of a channel 530 mayalso be approximately 50 microns in dimension or less. The protrusionsmay be made smooth and shallow in some examples to enhance comfort in auser while affording the necessary forced interaction for engagement ofa pumping action.

Diffusion “Pores” within the Body of an Encapsulated Hard Lens Device.

In some examples, a lens may be formed that has a hard encapsulatedelement within its body that may at least partially inhibit diffusion ofoxygen through the lens body. However in some examples, the hardencapsulated element may be a relatively simple passive element withoutstructures such as energization elements, circuits, and electroactivecomponents. In fact, in some examples, the hard encapsulated element maybe just a lens body. In a non-limiting example, such a composite lensmay be used to add physical tension to reshape a user's cornea.Referring to FIG. 6, an illustration of a lens with an encapsulated hardlens device is provided. A hard impermeable element 610 may beencapsulated in a soft lens skirt 620. Nevertheless, the fluids at thesurface of the user's eye under the hard lens portion may experience adeficit of oxygen during use where some of the strategies discussedherein may be helpful.

Referring to FIG. 7A, the hard lens element 700 is illustrated with apore 720 being cut by an exemplary laser irradiation 710. The pore 720may be a structural element that may be formed small enough in dimensionnot to interfere with vision. Nevertheless, the pore 720 may allowoxygen to diffuse through the hard lens element 700 body. Continuingwith FIG. 7B, the impermeable, hard lens element 700 with a pore 720 maybe encapsulated with hydrogel. The hydrogel may form the lens skirt 740and fill in the pore 741. As mentioned in concert with an advanced lens,such a pore particularly when backfilled with hydrogel may provide animprovement of oxygen diffusion amounts to the region under the lensstructure.

Oxygen Absorption and Desorption within the Body of a Contact Lens withan Encapsulated Hard Lens Element

Another manner to increase oxygen in the space between a contact lenswith an encapsulated hard lens element and the eye surface may be tostore an increased level of oxygen in the body of the lens. Theincreased level may be imparted to the lens by storing the lens in apressurized oxygen environment before packaging the lens. There may be anumber of material additions to layers in the lens that may impart theability to store oxygen from the pressurized atmosphere. Ideally thematerials that store the oxygen will desorb the oxygen as the level ofoxygen in its vicinity drops.

Referring to FIG. 8, a layer of absorptive material 830 may be embeddedwithin a contact lens with a hard lens element 810 and a hydrogel skirt820. In some examples, the absorptive material 830 may be deposited onthe surface of the hard lens element 810. In other examples, it may beembedded within the hydrogel skirt layer as a film or as in entrappeddiscrete elements. In some examples, the absorptive material 830 may besynthetic organometallic moieties based upon natural oxygen transportmolecules or may be biological oxygen transport molecules such ashemoglobin, hemocyanin, another porphyrin based species or another metalorganic framework molecular species. The absorptive material 830 maycomprise metallic species such as iron, copper, and zirconium asnon-limiting examples. These organometallic species may be integratedinto the hydrogel layer and may reversibly desorb oxygen into thehydrogel layer. Other similar organic molecules may be embedded toperform a similar function.

In other examples, the absorptive material 830 may comprise absorptiveparticles, such as zeolites that may be charged with oxygen. Theparticles may maintain an equilibrium level of oxygen in theirsurroundings. Therefore, when a package containing the advanced contactlens device is opened for use, a release of oxygen may occur, and theabsorptive particle may begin desorbing oxygen. In some examples, theabsorptive material may include zeolites of various composition such assodium, cerium, silicon and aluminum for example. In other examples theabsorptive/adsorptive material may comprise polymers and doped polymerswhich absorb oxygen, such as polymers with unsaturated regions orphenolic regions in the backbone. Polymers may be doped with otherspecies such as copper for example in a polyester and poly-butadienestructure. A super saturation of these absorptive particles under highpressure, high concentration and/or high partial pressure of oxygen, mayresult in a material that releases oxygen in low levels over time whenthe oxygen level in the ambient drops.

Materials for Lens Formation and Lens Skirts

Microinjection molding examples may include, for example, a poly(4-methylpent-1-ene) copolymer resin are used to form lenses with adiameter of between about 6 mm to 10 mm and a front surface radius ofbetween about 6 mm and 10 mm and a rear surface radius of between about6 mm and 10 mm and a center thickness of between about 0.050 mm and 1.0mm. Some examples include an hard lens element with diameter of about8.9 mm and a front surface radius of about 7.9 mm and a rear surfaceradius of about 7.8 mm and a center thickness of about 0.200 mm and anedge thickness of about 0.050 mm.

The hard lens element 600 illustrated in FIG. 6 may be placed in a moldpart utilized to form an ophthalmic lens. The material of mold parts mayinclude, for example, a polyolefin of one or more of: polypropylene,polystyrene, polyethylene, polymethyl methacrylate, and modifiedpolyolefins. Other molds may include a ceramic or metallic material.

A preferred alicyclic co-polymer contains two different alicyclicpolymers. Various grades of alicyclic co-polymers may have glasstransition temperatures ranging from 105° C. to 160° C.

In some examples, the molds of the present invention may containpolymers such as polypropylene, polyethylene, polystyrene, polymethylmethacrylate, modified polyolefins containing an alicyclic moiety in themain chain and cyclic polyolefins. This blend may be used on either orboth mold halves, where it is preferred that this blend is used on theback curve and the front curve consists of the alicyclic co-polymers.

In some preferred methods of making molds according to the presentinvention, injection molding is utilized according to known techniques,however, examples may also include molds fashioned by other techniquesincluding, for example: lathing, diamond turning, or laser cutting.

In some examples, a preferred lens material includes a siliconecontaining component. A “silicone-containing component” is one thatcontains at least one [—Si—O—] unit in a monomer, macromer orprepolymer. Preferably, the total Si and attached O are present in thesilicone-containing component in an amount greater than about 20 weightpercent, and more preferably greater than 30 weight percent of the totalmolecular weight of the silicone-containing component. Usefulsilicone-containing components preferably comprise polymerizablefunctional groups such as acrylate, methacrylate, acrylamide,methacrylamide, vinyl, N-vinyl lactam, N-vinylamide, and styrylfunctional groups.

In some examples, the ophthalmic lens skirt, also called aninsert-encapsulating layer, that surrounds the insert or hard lenselement may be comprised of standard hydrogel ophthalmic lensformulations. Exemplary materials with characteristics that may providean acceptable match to numerous insert materials may include, theNarafilcon family (including Narafilcon A and Narafilcon B), and theEtafilcon family (including Etafilcon A). A more technically inclusivediscussion follows on the nature of materials consistent with the artherein. One ordinarily skilled in the art may recognize that othermaterial other than those discussed may also form an acceptableenclosure or partial enclosure of the sealed and encapsulated insertsand should be considered consistent and included within the scope of theclaims.

Suitable silicone containing components include compounds of Formula I

where

R¹ is independently selected from monovalent reactive groups, monovalentalkyl groups, or monovalent aryl groups, any of the foregoing which mayfurther comprise functionality selected from hydroxy, amino, oxa,carboxy, alkyl carboxy, alkoxy, amido, carbamate, carbonate, halogen orcombinations thereof; and monovalent siloxane chains comprising 1-100Si—O repeat units which may further comprise functionality selected fromalkyl, hydroxy, amino, oxa, carboxy, alkyl carboxy, alkoxy, amido,carbamate, halogen or combinations thereof;

where b=0 to 500, where it is understood that when b is other than 0, bis a distribution having a mode equal to a stated value;

wherein at least one R¹ comprises a monovalent reactive group, and insome examples between one and 3 R¹ comprise monovalent reactive groups.

As used herein “monovalent reactive groups” are groups that may undergofree radical and/or cationic polymerization. Non-limiting examples offree radical reactive groups include (meth)acrylates, styryls, vinyls,vinyl ethers, C₁₋₆alkyl(meth)acrylates, (meth)acrylamides,C₁₋₆alkyl(meth)acrylamides, N-vinyllactams, N-vinylamides,C₂₋₁₂alkenyls, C₂₋₁₂alkenylphenyls, C₂₋₁₂alkenylnaphthyls,C₂₋₆alkenylphenylC₁₋₆alkyls, O-vinylcarbamates and O-vinylcarbonates.Non-limiting examples of cationic reactive groups include vinyl ethersor epoxide groups and mixtures thereof. In one embodiment the freeradical reactive groups comprises (meth)acrylate, acryloxy,(meth)acrylamide, and mixtures thereof.

Suitable monovalent alkyl and aryl groups include unsubstitutedmonovalent C₁ to C₁₆alkyl groups, C₆-C₁₄ aryl groups, such assubstituted and unsubstituted methyl, ethyl, propyl, butyl,2-hydroxypropyl, propoxypropyl, polyethyleneoxypropyl, combinationsthereof and the like.

In one example, b is zero, one R¹ is a monovalent reactive group, and atleast 3 R¹ are selected from monovalent alkyl groups having one to 16carbon atoms, and in another example from monovalent alkyl groups havingone to 6 carbon atoms. Non-limiting examples of silicone components ofthis embodiment include2-methyl-2-hydroxy-3-[3-[1,3,3,3-tetramethyl-1-[(trimethylsilyl)oxy]disiloxanyl]propoxy]propylester (“SiGMA”), 2-hydroxy-3-methacryloxypropyloxypropyl-tris(trimethylsiloxy)silane, 3-methacryloxypropyltris(trimethylsiloxy)silane(“TRIS”), 3-methacryloxypropylbis(trimethylsiloxy)methylsilane and3-methacryloxypropylpentamethyl disiloxane.

In another example, b is 2 to 20, 3 to 15 or in some examples 3 to 10;at least one terminal R¹ comprises a monovalent reactive group and theremaining R¹ are selected from monovalent alkyl groups having 1 to 16carbon atoms, and in another embodiment from monovalent alkyl groupshaving 1 to 6 carbon atoms. In yet another embodiment, b is 3 to 15, oneterminal R¹ comprises a monovalent reactive group, the other terminal R¹comprises a monovalent alkyl group having 1 to 6 carbon atoms and theremaining R¹ comprise monovalent alkyl group having 1 to 3 carbon atoms.Non-limiting examples of silicone components of this embodiment include(mono-(2-hydroxy-3-methacryloxypropyl)-propyl ether terminatedpolydimethylsiloxane (400-1000 MW)) (“OH-mPDMS”), monomethacryloxypropylterminated mono-n-butyl terminated polydimethylsiloxanes (800-1000 MW),(“mPDMS”).

In another example, b is 5 to 400 or from 10 to 300, both terminal R¹comprise monovalent reactive groups and the remaining R¹ areindependently selected from monovalent alkyl groups having 1 to 18carbon atoms, which may have ether linkages between carbon atoms and mayfurther comprise halogen.

In one example, where a silicone hydrogel lens is desired, the lens ofthe present invention will be made from a reactive mixture comprising atleast about 20 and preferably between about 20 and 70% wt siliconecontaining components based on total weight of reactive monomercomponents from which the polymer is made.

In another embodiment, one to four R¹ comprises a vinyl carbonate orcarbamate of the formula:

wherein: Y denotes O—, S— or NH—;

R denotes, hydrogen or methyl; d is 1, 2, 3 or 4; and q is 0 or 1.

The silicone-containing vinyl carbonate or vinyl carbamate monomersspecifically include:1,3-bis[4-(vinyloxycarbonyloxy)but-1-yl]tetramethyl-disiloxane;3-(vinyloxycarbonylthio) propyl-[tris (trimethylsiloxy)silane];3-[tris(trimethylsiloxy)silyl] propyl allyl carbamate;3-[tris(trimethylsiloxy)silyl] propyl vinyl carbamate;trimethylsilylethyl vinyl carbonate; trimethylsilylmethyl vinylcarbonate, and

Where biomedical devices with modulus below about 200 are desired, onlyone R¹ shall comprise a monovalent reactive group and no more than twoof the remaining R¹ groups will comprise monovalent siloxane groups.

Another class of silicone-containing components includes polyurethanemacromers of the following formulae:

(*D*A*D*G)_(a)*D*D*E¹;

E(*D*G*D*A)_(a)*D*G*D*E¹ or;

E(*D*A*D*G)_(a)*D*A*D*E¹  Formulae IV-VI

wherein:

D denotes an alkyl diradical, an alkyl cycloalkyl diradical, acycloalkyl diradical, an aryl diradical or an alkylaryl diradical having6 to 30 carbon atoms,

G denotes an alkyl diradical, a cycloalkyl diradical, an alkylcycloalkyl diradical, an aryl diradical or an alkylaryl diradical having1 to 40 carbon atoms and which may contain ether, thio or amine linkagesin the main chain;

* denotes a urethane or ureido linkage;

_(a) is at least 1;

A denotes a divalent polymeric radical of formula:

R11 independently denotes an alkyl or fluoro-substituted alkyl grouphaving 1 to 10 carbon atoms, which may contain ether linkages betweencarbon atoms; y is at least 1; and p provides a moiety weight of 400 to10,000; each of E and E1 independently denotes a polymerizableunsaturated organic radical represented by formula:

wherein: R12 is hydrogen or methyl; R13 is hydrogen, an alkyl radicalhaving 1 to 6 carbon atoms, or a —CO—Y—R15 radical wherein Y is —O—,Y—S— or —NH—; R14 is a divalent radical having 1 to 12 carbon atoms; Xdenotes —CO— or —OCO—; Z denotes —O— or —NH—; Ar denotes an aromaticradical having 6 to 30 carbon atoms; w is 0 to 6; x is 0 or 1; y is 0 or1; and z is 0 or 1.

A preferred silicone-containing component is a polyurethane macromerrepresented by the following formula:

wherein R16 is a diradical of a diisocyanate after removal of theisocyanate group, such as the diradical of isophorone diisocyanate.Another suitable silicone containing macromer is compound of formula X(in which x+y is a number in the range of 10 to 30) formed by thereaction of fluoroether, hydroxy-terminated polydimethylsiloxane,isophorone diisocyanate and isocyanatoethylmethacrylate.

Other silicone containing components suitable for use in this inventioninclude macromers containing polysiloxane, polyalkylene ether,diisocyanate, polyfluorinated hydrocarbon, polyfluorinated ether andpolysaccharide groups; polysiloxanes with a polar fluorinated graft orside group having a hydrogen atom attached to a terminaldifluoro-substituted carbon atom; hydrophilic siloxanyl methacrylatescontaining ether and siloxanyl linkages and crosslinkable monomerscontaining polyether and polysiloxanyl groups. Any of the foregoingpolysiloxanes may also be used as the silicone containing component inthe present invention.

Formulations of the skirt materials as have been describe may beconfigured to create a skirt layer that has structural strength tomaintain channels of various sizes while being worn upon a user's eyes.In some examples, the channels may be molded into the skirt as it isformed. In other examples, the channels may be cut or eroded from themolded material. The skirt material may also be configured so that ithas an optical index of refraction that closely matches that of tearfluid for an average human user. Thus, the presence of molding features,which may occur in the optic zone of the aforementioned examples ofadvanced contact lenses may be rendered non optically active when theyfill with tear fluid after being placed upon the user's eyes. Asmentioned previously, various shapes and profiles of the channels may beformed for different purposes such as enhancing directional flow offluids within the channels.

The methods and apparatus to enhance oxygenation in regions proximate toan electroactive component in a biomedical device may be designed andincorporated into numerous other types of biomedical devices. Thebiomedical devices may be, for example, implantable electronic devices,such as pacemakers and micro-energy harvesters, electronic pills formonitoring and/or testing a biological function, surgical devices withactive components, ophthalmic devices, and the like.

Specific examples have been described to illustrate embodiments for theformation, methods of formation, and apparatus of formation ofbiocompatible devices to enhance levels of oxygen in regions of tissueof a user of the electroactive biomedical device. These examples are forillustration and are not intended to limit the scope of the claims inany manner. Accordingly, the description is intended to embrace allembodiments that may be apparent to those skilled in the art.

What is claimed is:
 1. A contact lens comprising: a hydrogel skirt,wherein the hydrogel skirt is molded into a shape of the contact lens,with an arcuate back surface placed proximate to a user's cornea duringa use of the contact lens; an encapsulated hard lens element, whereinthe encapsulated hard lens element is gas impermeable and impermeable tofluid flow through its body, wherein the encapsulated hard lens elementis encapsulated within the hydrogel skirt; a first region of thehydrogel skirt, wherein the first region of the hydrogel skirt is thatportion of the hydrogel skirt that is between a surface of theencapsulated hard lens element and a cornea of a user during the use ofthe contact lens; and a means within the contact lens of enhancingoxygen levels within a fluid in contact with the first region.
 2. Thecontact lens according to claim 1, wherein the means within the contactlens of enhancing oxygen levels within the fluid in contact with thefirst region comprises at least a first pore in the hard lens element,wherein the pore traverses the body of the hard lens element.
 3. Thecontact lens according to claim 2, wherein the pore traverses a body ofa spacer located within the hard lens element.
 4. The contact lensaccording to claim 2, wherein the pore is back-filled with a siliconecontaining material.
 5. The contact lens according to claim 4, whereinthe first pore is one of a plurality of pores, wherein the plurality ofpores traverse the body of the hard lens element.
 6. The contact lensaccording to claim 5, wherein the plurality of pores are back-filledwith the silicone containing material.
 7. The contact lens according toclaim 1, wherein the means within the contact lens of enhancing oxygenlevels comprises a layer of absorptive material, wherein the absorptivematerial absorbs oxygen gas.
 8. The contact lens according to claim 7,wherein the absorptive material comprises hemoglobin.
 9. The contactlens according to claim 7, wherein the absorptive material compriseshemocyanin.
 10. The contact lens according to claim 7, wherein theabsorptive material comprises a porphyrin based material.
 11. Thecontact lens according to claim 7, wherein the absorptive materialcomprises a metal organic framework molecular species.
 12. A method ofenhancing oxygen levels at a user's cornea when the user wears a contactlens, the method comprising: forming a pore through a contact lensencapsulated hard lens element; backfilling the pore with a siliconecontaining polymer; and providing the contact lens comprising thecontact lens encapsulated hard lens element, wherein during the use ofthe contact lens, oxygen diffuses through the pore with the siliconecontaining polymer to a region of tear fluid underneath the contactlens.
 13. A method of enhancing oxygen levels at a user's cornea whenthe user wears a contact lens, the method comprising: forming a layer ofoxygen absorptive material within a body of the contact lens; placingthe contact lens in an ambient with high partial pressure of oxygen; andproviding the contact lens, wherein during a use of the contact lens,oxygen diffuses from the absorptive material to a region of tear fluidunderneath the contact lens.